Using simplificative assumptions, we show that a redundant configuration of diluted apertures should permit an easier exoplanet detection than a non-redundant one. This result assumes that after coronagraphy the planet appears over an uniform background whose statistical fluctuation is the unique source of noise. The detection is made using a matched filter, cross-correlating the observed image with the telescope array PSF. In that case, the relevant parameter appears to be the integral of the modulus squared of the aperture MTF.